90.00.00 GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS (for more detailed headings, see the Geophysics Appendix)
- 91.00.00 Solid Earth physics
- 92.00.00 Hydrospheric and atmospheric geophysics (2)
- 93.00.00 Geophysical observations, instrumentation, and techniques
- 94.00.00 Physics of the ionosphere and magnetosphere
- 95.00.00 Fundamental astronomy and astrophysics; instrumentation, techniques, and astronomical observations
- 96.00.00 Solar system; planetology
- 97.00.00 Stars (for relativistic stars, see 04.40.Dg in general relativity and gravitation) (3)
- 98.00.00 Stellar systems; interstellar medium; galactic and extragalactic objects and systems; the Universe (2)
- 99.10.-x Errata and other corrections